The S&P hit a high of 2,120.92. The Nasdaq rose to 5,100.371, the highest since touching a record of 5,132.52 in March 2000.

"The difference today contrasting with back then is, you have a lot of mature companies like Microsoft, EMC and Intel that can be looked at as almost blue chip companies that pay relatively high dividends," said James Abate, chief investment officer of Centre Funds in New York, comparing the fresh Nasdaq highs with those in 2000, right before the Internet bubble burst.

"The froth really is in social media companies and when you compare it back then, the froth was pretty much everywhere."

At 1:03 p.m. EDT the Dow Jones industrial average was up 30.25 points, or 0.17 percent, at 18,088.94, the S&P 500 was up 6.04 points, or 0.29 percent, at 2,118.97 and the Nasdaq Composite was higher 38.50 points, or 0.76 percent, at 5,094.56.

Xerox slumped as much as 14 percent to a 52-week low of $11.32 after it cut its 2015 profit forecast, adding to a growing list of companies that have blamed a strong U.S. currency for weakened results or forecasts.

Comcast abandoned its proposed $45 billion merger with Time Warner Cable after U.S. regulators said the deal would give Comcast an unfair advantage in the Internet-based services market. Time Warner rose 3.7 percent to $154.41 while Comcast was up 0.8 percent at $57.73.

Mylan's shares rose 2.8 percent to $75.78 after the generic drugmaker said it would commence a formal offer to buy Perrigo. Perrigo was down 3 percent to $195.50 after it rejected the offer for the second time in a week.

Aerie Pharmaceuticals dived 60.6 percent to $13.96 after the company's lead experimental drug failed to show that it was superior to commonly prescribed eye-drops.

Biogen shares fell 5.8 percent to $405.10 after sales of its key oral multiple sclerosis drug fell on a sequential basis in the first quarter for the first time since its launch in 2013.

Advancing issues outnumbered declining ones on the NYSE by 1,491 to 1,433, for a 1.04-to-1 ratio on the upside; on the Nasdaq, 1,452 issues fell and 1,197 advanced for a 1.21-to-1 ratio favoring decliners.

The benchmark S&P 500 index was posting 16 new 52-week highs and 1 new lows; the Nasdaq Composite was recording 84 new highs and 16 new lows.